Following the steps in #18 I can get something similar if I hit numpad 0 which invokes a special edit mode. What is displayed is not the Now marker but the cursor for the special edit mode. 4 and 6 move this cursor left and right. Hitting numpad 0 again reverts the number pad back to its regular state.
 
If that is not the problem, it may be something specific to your setup. Are you using a US keyboard and Windows?

Impressive, Scook - you found it! Not sure how the numpad 0 key got in the mix after re-starting the system, etc., but I love it when a mystery is solved. Now I can go back to fiddling with the inline PRV and seeing if this old dog can learn a few new tricks. One downside to all the keyboard shortcuts is sometimes you hit a key by accident and wind up in a strange new world without a roadmap. Many thanks to you and Craig for helping me find my way back home.

If you find a predefined shortcut to be a problem, such as numpad 0, disable it by going into keyboard shortcut preferences and bind it to "Do nothing."

scook
Following the steps in #18 I can get something similar if I hit numpad 0 which invokes a special edit mode.

I was going to mention this earlier this morning but when he said it worked on one monitor and not the other...
 

rhenn
What's really weird is I have PRV open on my 2nd monitor, and Track View on my main. If I select and nudges notes in PRV, notes move properly in both views. But when I select the notes in the inline PRV, nudge keys have no effect.

 
I figured it was something else like a keybinding issue.

Nudge was working in the PRV but not the track view. This is because the special edit mode only works in the track view. The thing that tipped me off was

rhenn
 4. Set Track filter to Notes, maximized view

and the mention of 4 and 6 moving Now. Had the track not been maximized, the edit cursor would have been more obvious. By maximizing the track the edit cursor fills the screen and looks similar to Now although without the play head at the top.